How much does crosswind effect mid and large jets?

[Byrna]

Hello,

I wanted to get a feel for the stability of commercial jets like the 737-700 / A320 versus a 744 / A340 or mid-sized heavies like the 757/767/A330 under crosswind conditions.

I do flight simulation using Microsoft Flight Simulator 2004 but with add-on aircraft and a third-party weather-simulation add-on engine which can "smooth" the sudden "jolt" the plane can receive if using the default Microsoft FS2004 built-in weather engine.

But I just wanted to ask real-life pilots about cross-wind landings: Say you have no choice as there is a medium cross-wind (based on my knowledge, this would be 10-15 knots) but coming at a right angle to your landing runway (or pretty close to 90 degrees). You have no choice to land as this airport (e.g. Atlanta Hartsfield KATL or Munich EDDM) is one with only parallel runways. How does a Jumbo Jet react and how controllable is it under a 15 Kt. cross wind? How about a 737/A320 class mid-sized jet? At what point does it become unsafe to land a Jumbo (what crosswind speed?) or a 737/A320? Boeing's specs I believe have a max. x-wind of around 24 Kts...



John

[BOAC]

Crosswind 'limits' are set by the manufacturer by 'demonstration'. Airlines then normally choose something up to that speed. BA for the 737 was 40kts. It does not mean that is the real limit.

Cannot speak for Jumbo, but 737 is ok at that speed - needs a bit of 'work' though.:)

Try a search for crosswind and you will find a few threads and videos.

[Intruder]

747 crosswind limit is 30 knots. It looks weird, since the cockpit is over the upwind side stripe to touchdown, but it works.

[longarm]

A320/A321 is 33kts gusting up to 38kts.

[TopBunk]

Intruder

The BA 747-400 landing limits are 36kts dry, 32kts wet and 27kts with assymetric reverse!

All easily controllable in steady state wind conditions, but more interesting on, for example, LHR 27R or LGW 26L with the hangars:eek:

[Intruder]

Those limits may be in your airline, but not mine. They are 30 knots dry runway (T/O and landing), 25 wet runway. There is no separate number specified for asymmetric reverse (probably because we don't do that).

Our 747 Classic FHB is similar, except 30 kt allowed for wet runway takeoff. According to our FHB, the 30 kt limits are Boeing AFM numbers, and the 25 is a local number.

[Byrna]

Thank-you for the cross-wind speed limits but my question is more handling. If, say you have a METAR of 18015G25 at LHR (which is a 90 degree crosswind no matter which runway you choose), then how does a 744 handle versus the mid-sized 737 or A320? Do you actually feel the plane moving to the side (even if slight) as the gusts hit the plane or is it steady?

[TopBunk]

Intruder

I don't doubt that yours may be differennt, that is also why I quoted my airline!

For completeness, the take off crosswind limits we operate to are:
Dry 40kts, wet 25kts, contaminated 15kts.

The 40kts XWC takeoff is challenging in the rotation stage, having held 8 units of aileron in on the takeoff roll.....

[TopBunk]

Byrna

My judgement is (having flown the 737, A320 family and the 747-400) is:

747-400
1. Has more momentum, therefore 'rides' the bumps with less deflection
2. At average weights, has a higher final approach speed (typically 150+kts), and therefore needs to lay off less drift
3. Has a higher wing loading (see 1 above)
4. Has better ground effect helping the flare.
5. The pilots carry out fewer landings and have usually just completed a long duty period which can counter 1, 2, 3 and 4.
6. Higher risk of pod scrape

737-2/3/400
1. Lower wing loading, therefore easily bumped around (esp the -200)
2. -200 has lowest landing speed (along with A319) and therefore greatest amount of drift
3. Not much ground effect
4. Pilots in very good practice
5. 2 engines mean that the risk of pod scrape is low

A320 family
1. Not much difference in speeds and hence drift to the 737 family
2. A320/321 and 737-400 have similar approach speeds, and low pod scrap risk
3. Pilots similarly practiced
4. Airbus FBW has totally different handling characteristics to 'conventional' aircraft which can work for and against. Pilot Induced Oscillation (PIO) is possible causing some approach destabilisation.

Personal preference, well they each have their merits, but for controllability the 737-200 can't be beaten, as a modern workhorse in shorthaul the A320 is unrivalled, but the 747-400 is the Queen of the Skies.

[Intruder]

I haven't flown the small ones, but the 747 is relatively easy to handle in gusty crosswinds, with the Classic being more controllable than the -400.

One trap I've fallen into several times is putting in a final correction for landing (combination of track correction, wing down, and top rudder) too soon. With a low-level wind shear, setting up for conditions at 200-300' may put all that inertia on the wrong vector when the wind changes at 50-100'. I've found that "kicking out" a good portion of the crab angle just before (or during) the flare makes for more precise placement on the centerline. Having the ailerons moving (not just set) into the wind at touchdown also helps counter the inevitable upwind wing-up movement.

[scroggs]

I've flown both the B747 (200) and the A340 (300 and 600) and I'd rather have the Boeing in a strong, gusty crosswind any day! The lower wingloading of the 340 makes it a bit bouncy on a gusty day, and the 600 in particular can be a real handful because of slow control response and spool-up. The demonstrated crosswind limits on the A340 are quite high (33kts for the -300 and 37 kts for the -600), however. Due to the length of the -600, the flight deck can feel like it's over the grass before the drift is kicked off!

[king rooney]

Am only a lowly ppl holder, but am curious, what technique would one use to land say a 747 in a fairly strong crosswind? Is it the same as with a small plane, Warrior for example?

[Intruder]

General techniques are the same, and just as varied. Wing down is limited, though, because of the low-hanging engine nacelles.

[WHBM]

I am lowly PA28 driver as well. How can it be that something this small is qualified up to 20kts whereas the 747 in otherwise good conditions only goes up to 36kts. Would have thought the differential would be much greater.

[AlphaWhiskyRomeo]

I guess because the PA-28 lands at a lot lower speed, so it is easier to throw it around and land. More time for the Pilot and less stress on the airframe and u/c????

[Tarq57]

WHBM
Think kinetic energy (square of the speed etc).
Double the crosswind speed, you end up multiplying by 4 the potential side load on the gear. An increase from 20kt to 36 kt is very considerable. I've landed a C206 in 30g35 straight across, but that was made easy by having over a mile of runway, therefore higher landing speed, flapless. Most heavy pilots don't usually have that luxury.